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<h1 id="Exercises-Section-5-1"><a href="#Exercises-Section-5-1" class="headerlink" title="Exercises Section 5.1"></a>Exercises Section 5.1</h1><h2 id="Ex5-1"><a href="#Ex5-1" class="headerlink" title="Ex5.1"></a>Ex5.1</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">;		<span class="comment">// null statement</span></span><br></pre></td></tr></table></figure>

<h2 id="Ex5-2"><a href="#Ex5-2" class="headerlink" title="Ex5.2"></a>Ex5.2</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// block</span></span><br><span class="line">&#123;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-2"><a href="#Exercises-Section-5-2" class="headerlink" title="Exercises Section 5.2"></a>Exercises Section 5.2</h1><h2 id="Ex5-4"><a href="#Ex5-4" class="headerlink" title="Ex5.4"></a>Ex5.4</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line">a) <span class="keyword">while</span> (string::iterator iter != s.<span class="built_in">end</span>())  &#123; <span class="comment">/*... */</span> &#125;	<span class="comment">// 未初始化 iter 的值</span></span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">string::iterator iter = s.<span class="built_in">begin</span>();</span><br><span class="line"><span class="keyword">while</span> (iter != s.<span class="built_in">end</span>()) &#123; <span class="comment">/*... */</span> &#125;</span><br><span class="line"></span><br><span class="line">b) <span class="keyword">while</span> (<span class="type">bool</span> status = <span class="built_in">find</span>(word)) &#123; <span class="comment">/*... */</span> &#125;	</span><br><span class="line">   <span class="keyword">if</span> (!status)  &#123; <span class="comment">/*... */</span> &#125;       <span class="comment">// status 不能在 while 循环外获取</span></span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line"><span class="keyword">while</span> (<span class="type">bool</span> status = <span class="built_in">find</span>(word)) </span><br><span class="line">&#123; </span><br><span class="line">	<span class="keyword">if</span> (!status)  &#123; <span class="comment">/*... */</span> &#125; </span><br><span class="line">	<span class="comment">/*... */</span> </span><br><span class="line">&#125;       </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-3-1"><a href="#Exercises-Section-5-3-1" class="headerlink" title="Exercises Section 5.3.1"></a>Exercises Section 5.3.1</h1><h2 id="Ex5-7"><a href="#Ex5-7" class="headerlink" title="Ex5.7"></a>Ex5.7</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br></pre></td><td class="code"><pre><span class="line">a) <span class="keyword">if</span> (ival1 != ival2)</span><br><span class="line">	   ival1 = ival2</span><br><span class="line">   <span class="keyword">else</span> ival1 = ival2 = <span class="number">0</span>;</span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line"><span class="keyword">if</span> (ival1 != ival2)</span><br><span class="line">	ival1 = ival2;</span><br><span class="line"><span class="keyword">else</span> </span><br><span class="line">	ival1 = ival2 = <span class="number">0</span>;</span><br><span class="line">    </span><br><span class="line">b) <span class="keyword">if</span> (ival &lt; minval)</span><br><span class="line">	   minval = ival;</span><br><span class="line">       occurs = <span class="number">1</span>;     </span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line"><span class="keyword">if</span> (ival &lt; minval)</span><br><span class="line">	minval = ival;</span><br><span class="line">	occurs += <span class="number">1</span>;</span><br><span class="line">    </span><br><span class="line">c) <span class="keyword">if</span> (<span class="type">int</span> ival = <span class="built_in">get_value</span>())</span><br><span class="line">	   cout &lt;&lt; <span class="string">&quot;ival = &quot;</span> &lt;&lt; ival &lt;&lt; endl;</span><br><span class="line">   <span class="keyword">if</span> (!ival)</span><br><span class="line">   	   cout &lt;&lt; <span class="string">&quot;ival = 0\n&quot;</span>;      </span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line"><span class="type">int</span> ival = <span class="built_in">get_value</span>();</span><br><span class="line"><span class="keyword">if</span> (!ival)</span><br><span class="line">	cout &lt;&lt; <span class="string">&quot;ival = 0\n&quot;</span>;</span><br><span class="line"><span class="keyword">else</span> </span><br><span class="line">	cout &lt;&lt; <span class="string">&quot;ival = &quot;</span> &lt;&lt; ival &lt;&lt; endl;</span><br><span class="line">    </span><br><span class="line">d) <span class="keyword">if</span> (ival = <span class="number">0</span>)</span><br><span class="line">	   ival = <span class="built_in">get_value</span>();</span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line"><span class="keyword">if</span> (ival == <span class="number">0</span>)</span><br><span class="line">	ival = <span class="built_in">get_value</span>();</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-8"><a href="#Ex5-8" class="headerlink" title="Ex5.8"></a>Ex5.8</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="string">&quot;dangling else&quot;</span>：当有多个 <span class="keyword">if</span> 嵌套时，如果只有一个 <span class="keyword">else</span>，那么该 <span class="keyword">else</span> 在没有明确表示匹配哪个 <span class="keyword">if</span> 时，会自动匹配离它最近的 <span class="keyword">if</span>。 </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-3-2"><a href="#Exercises-Section-5-3-2" class="headerlink" title="Exercises Section 5.3.2"></a>Exercises Section 5.3.2</h1><h2 id="Ex5-9"><a href="#Ex5-9" class="headerlink" title="Ex5.9"></a>Ex5.9</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> a_count = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> e_count = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> i_count = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> o_count = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> u_count = <span class="number">0</span>;</span><br><span class="line">    string s = <span class="string">&quot;&quot;</span>;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Please enter a string: &quot;</span> &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">getline</span>(cin, s);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (<span class="type">char</span> c : s)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (c == <span class="string">&#x27;a&#x27;</span> || c == <span class="string">&#x27;A&#x27;</span>)</span><br><span class="line">            ++a_count;</span><br><span class="line">        <span class="keyword">if</span> (c == <span class="string">&#x27;e&#x27;</span> || c == <span class="string">&#x27;E&#x27;</span>) </span><br><span class="line">            ++e_count;</span><br><span class="line">        <span class="keyword">if</span> (c == <span class="string">&#x27;i&#x27;</span> || c == <span class="string">&#x27;I&#x27;</span>)</span><br><span class="line">            ++i_count;</span><br><span class="line">        <span class="keyword">if</span> (c == <span class="string">&#x27;o&#x27;</span> || c == <span class="string">&#x27;O&#x27;</span>)</span><br><span class="line">            ++o_count;</span><br><span class="line">        <span class="keyword">if</span> (c == <span class="string">&#x27;u&#x27;</span> || c == <span class="string">&#x27;U&#x27;</span>)</span><br><span class="line">            ++u_count;</span><br><span class="line">    &#125;</span><br><span class="line">    cout &lt;&lt; a_count &lt;&lt; <span class="string">&quot; &quot;</span> &lt;&lt; e_count &lt;&lt; <span class="string">&quot; &quot;</span> &lt;&lt; i_count &lt;&lt; <span class="string">&quot; &quot;</span>  &lt;&lt; o_count &lt;&lt; <span class="string">&quot; &quot;</span> &lt;&lt; u_count &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-10"><a href="#Ex5-10" class="headerlink" title="Ex5.10"></a>Ex5.10</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">unsigned</span> aCnt = <span class="number">0</span>, eCnt = <span class="number">0</span>, iCnt = <span class="number">0</span>, oCnt = <span class="number">0</span>, uCnt = <span class="number">0</span>;</span><br><span class="line">    <span class="type">char</span> ch;</span><br><span class="line">    <span class="keyword">while</span> (cin &gt;&gt; ch)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">switch</span>(ch)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;a&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;A&#x27;</span>:</span><br><span class="line">                ++aCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;e&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;E&#x27;</span>:</span><br><span class="line">                ++eCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;i&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;I&#x27;</span>:</span><br><span class="line">                ++iCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;o&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;O&#x27;</span>:</span><br><span class="line">                ++oCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;u&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;U&#x27;</span>:</span><br><span class="line">                ++uCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel a: \t&quot;</span> &lt;&lt; aCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel e: \t&quot;</span> &lt;&lt; eCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel i: \t&quot;</span> &lt;&lt; iCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel o: \t&quot;</span> &lt;&lt; oCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel u: \t&quot;</span> &lt;&lt; uCnt &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-11"><a href="#Ex5-11" class="headerlink" title="Ex5.11"></a>Ex5.11</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">unsigned</span> aCnt = <span class="number">0</span>, eCnt = <span class="number">0</span>, iCnt = <span class="number">0</span>, oCnt = <span class="number">0</span>, uCnt = <span class="number">0</span>, blackCnt = <span class="number">0</span>;</span><br><span class="line">    <span class="type">char</span> ch;</span><br><span class="line">    <span class="keyword">while</span> ((ch = cin.<span class="built_in">get</span>()) != EOF)     <span class="comment">// cin 会自动忽略所有空白字符，故而使用cin.get()</span></span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">switch</span>(ch)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;a&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;A&#x27;</span>:</span><br><span class="line">                ++aCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;e&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;E&#x27;</span>:</span><br><span class="line">                ++eCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;i&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;I&#x27;</span>:</span><br><span class="line">                ++iCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;o&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;O&#x27;</span>:</span><br><span class="line">                ++oCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27;u&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;U&#x27;</span>:</span><br><span class="line">                ++uCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">            <span class="keyword">case</span> <span class="string">&#x27; &#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;\t&#x27;</span>: <span class="keyword">case</span> <span class="string">&#x27;\n&#x27;</span>:</span><br><span class="line">                ++blackCnt;</span><br><span class="line">                <span class="keyword">break</span>;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel a: \t&quot;</span> &lt;&lt; aCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel e: \t&quot;</span> &lt;&lt; eCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel i: \t&quot;</span> &lt;&lt; iCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel o: \t&quot;</span> &lt;&lt; oCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of vowel u: \t&quot;</span> &lt;&lt; uCnt &lt;&lt; endl;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Number of blank spaces, tabs and newlines: \t&quot;</span> &lt;&lt; blackCnt &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-13"><a href="#Ex5-13" class="headerlink" title="Ex5.13"></a>Ex5.13</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br></pre></td><td class="code"><pre><span class="line">a) </span><br><span class="line">	<span class="type">unsigned</span> aCnt = <span class="number">0</span>, eCnt = <span class="number">0</span>, iouCnt = <span class="number">0</span>;</span><br><span class="line">    <span class="type">char</span> ch = <span class="built_in">next_text</span>();</span><br><span class="line">    <span class="keyword">switch</span>(ch) 			<span class="comment">// 缺少 break</span></span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> <span class="string">&#x27;a&#x27;</span>:   aCnt++;</span><br><span class="line">        <span class="keyword">case</span> <span class="string">&#x27;e&#x27;</span>:   eCnt++;</span><br><span class="line">        <span class="keyword">default</span>:    iouCnt++;</span><br><span class="line">    &#125;</span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">	<span class="type">unsigned</span> aCnt = <span class="number">0</span>, eCnt = <span class="number">0</span>, iouCnt = <span class="number">0</span>;</span><br><span class="line">	<span class="type">char</span> ch = <span class="built_in">next_text</span>();</span><br><span class="line">	<span class="keyword">switch</span>(ch) 			</span><br><span class="line">	&#123;</span><br><span class="line">    	<span class="keyword">case</span> <span class="string">&#x27;a&#x27;</span>:   aCnt++; <span class="keyword">break</span>;</span><br><span class="line">    	<span class="keyword">case</span> <span class="string">&#x27;e&#x27;</span>:   eCnt++; <span class="keyword">break</span>;</span><br><span class="line">    	<span class="keyword">default</span>:    iouCnt++; <span class="keyword">break</span>;</span><br><span class="line">	&#125;</span><br><span class="line"></span><br><span class="line">b)  </span><br><span class="line">	<span class="type">unsigned</span> index = <span class="built_in">some_value</span>();</span><br><span class="line">    <span class="keyword">switch</span>(index) </span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">1</span>:</span><br><span class="line">            <span class="type">int</span> ix = <span class="built_in">get_value</span>();</span><br><span class="line">            ivec[ix] = index;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">default</span>:</span><br><span class="line">            ix = ivec.<span class="built_in">size</span>() - <span class="number">1</span>;   <span class="comment">// 上个 case 初始化的变量不能在下一个case 中使用</span></span><br><span class="line">            ivec[ix] = index;</span><br><span class="line">    &#125;</span><br><span class="line">	<span class="comment">// 修改如下</span></span><br><span class="line">	<span class="type">unsigned</span> index = <span class="built_in">some_value</span>();</span><br><span class="line">    <span class="keyword">switch</span>(index) </span><br><span class="line"> 	&#123;</span><br><span class="line">    	<span class="keyword">case</span> <span class="number">1</span>:</span><br><span class="line">        	<span class="type">int</span> ix = <span class="built_in">get_value</span>();</span><br><span class="line">        	ivec[ix] = index;</span><br><span class="line">        	<span class="keyword">break</span>;</span><br><span class="line">    	<span class="keyword">default</span>:</span><br><span class="line">        	<span class="type">int</span> ix = ivec.<span class="built_in">size</span>() - <span class="number">1</span>;   </span><br><span class="line">        	ivec[ix] = index;</span><br><span class="line">        	<span class="keyword">break</span>;</span><br><span class="line">    	&#125;</span><br><span class="line">    </span><br><span class="line">c) </span><br><span class="line">    <span class="type">unsigned</span> evenCnt = <span class="number">0</span>, oddCnt = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> digit = <span class="built_in">get_num</span>() % <span class="number">10</span>;</span><br><span class="line">    <span class="keyword">switch</span>(digit)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">1</span>, <span class="number">3</span>, <span class="number">5</span>, <span class="number">7</span>, <span class="number">9</span>:		<span class="comment">// 必须分开写，不能使用逗号</span></span><br><span class="line">            oddCnt++;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">2</span>, <span class="number">4</span>, <span class="number">6</span>, <span class="number">8</span>, <span class="number">10</span>:</span><br><span class="line">            evenCnt++;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">	<span class="type">unsigned</span> evenCnt = <span class="number">0</span>, oddCnt = <span class="number">0</span>;</span><br><span class="line">    <span class="type">int</span> digit = <span class="built_in">get_num</span>() % <span class="number">10</span>;</span><br><span class="line">    <span class="keyword">switch</span>(digit)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">1</span>: <span class="keyword">case</span> <span class="number">3</span>: <span class="keyword">case</span> <span class="number">5</span>: <span class="keyword">case</span> <span class="number">7</span>: <span class="keyword">case</span> <span class="number">9</span>:</span><br><span class="line">            oddCnt++;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">2</span>: <span class="keyword">case</span> <span class="number">4</span>: <span class="keyword">case</span> <span class="number">6</span>: <span class="keyword">case</span> <span class="number">8</span>: <span class="keyword">case</span> <span class="number">10</span>:</span><br><span class="line">            evenCnt++;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">d)</span><br><span class="line">	<span class="type">unsigned</span> ival = <span class="number">512</span>, jval = <span class="number">1024</span>, kval = <span class="number">4096</span>;</span><br><span class="line">    <span class="type">unsigned</span> bufsize;</span><br><span class="line">    <span class="type">unsigned</span> swt = <span class="built_in">get_bufCnt</span>();</span><br><span class="line">    <span class="keyword">switch</span>(swt)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> ival:				<span class="comment">// case 后面不能跟变量</span></span><br><span class="line">            bufsize = ival + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> jval:</span><br><span class="line">            bufsize = jval + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> kval:</span><br><span class="line">            bufsize = kval + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">    <span class="type">unsigned</span> ival = <span class="number">512</span>, jval = <span class="number">1024</span>, kval = <span class="number">4096</span>;</span><br><span class="line">    <span class="type">unsigned</span> bufsize;</span><br><span class="line">    <span class="type">unsigned</span> swt = <span class="built_in">get_bufCnt</span>();</span><br><span class="line">    <span class="keyword">switch</span>(swt)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">512</span>:</span><br><span class="line">            bufsize = ival + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">1024</span>:</span><br><span class="line">            bufsize = jval + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> <span class="number">4096</span>:</span><br><span class="line">            bufsize = kval + <span class="built_in">sizeof</span>(<span class="type">int</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-4-1"><a href="#Exercises-Section-5-4-1" class="headerlink" title="Exercises Section 5.4.1"></a>Exercises Section 5.4.1</h1><h2 id="Ex5-14"><a href="#Ex5-14" class="headerlink" title="Ex5.14"></a>Ex5.14</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> max_cnt = <span class="number">0</span>, cnt = <span class="number">0</span>;</span><br><span class="line">    string max_word, word, front_word;</span><br><span class="line">    <span class="keyword">while</span> (cin &gt;&gt; word)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (front_word.<span class="built_in">empty</span>())</span><br><span class="line">        &#123;</span><br><span class="line">            max_word = word;</span><br><span class="line">            front_word = word;</span><br><span class="line">            </span><br><span class="line">            ++cnt;</span><br><span class="line">            max_cnt = cnt;</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">else</span> </span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">if</span> (front_word == word)</span><br><span class="line">            &#123;</span><br><span class="line">                ++cnt;</span><br><span class="line">                front_word = word;</span><br><span class="line">                <span class="keyword">if</span> (max_cnt &lt; cnt)</span><br><span class="line">                &#123;</span><br><span class="line">                    max_cnt = cnt;</span><br><span class="line">                    max_word = word;</span><br><span class="line">                &#125;</span><br><span class="line">            &#125;</span><br><span class="line">            <span class="keyword">else</span> </span><br><span class="line">            &#123;</span><br><span class="line">                front_word = word;</span><br><span class="line">                cnt = <span class="number">1</span>;</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">if</span> (max_cnt &gt; <span class="number">1</span>)</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;The &quot;</span> &lt;&lt; max_word &lt;&lt; <span class="string">&quot; occurred &quot;</span> &lt;&lt; max_cnt &lt;&lt; <span class="string">&quot; times&quot;</span> &lt;&lt; endl;</span><br><span class="line">    <span class="keyword">else</span> </span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;No word occurred more than two times.&quot;</span> &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-4-2"><a href="#Exercises-Section-5-4-2" class="headerlink" title="Exercises Section 5.4.2"></a>Exercises Section 5.4.2</h1><h2 id="Ex5-15"><a href="#Ex5-15" class="headerlink" title="Ex5.15"></a>Ex5.15</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line">a)</span><br><span class="line">	<span class="keyword">for</span> (<span class="type">int</span> ix = <span class="number">0</span>; ix != sz; ++ix) &#123; <span class="comment">/*... */</span> &#125;</span><br><span class="line">    <span class="keyword">if</span> (ix != sz)	<span class="comment">// ix 不能在 for 循环外使用</span></span><br><span class="line">    	<span class="comment">// ...</span></span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">	<span class="type">int</span> ix = <span class="number">0</span>;</span><br><span class="line">    <span class="keyword">for</span> (; ix != sz; ++ix) &#123; <span class="comment">/* ... */</span> &#125;</span><br><span class="line">    <span class="keyword">if</span> (ix != sz)</span><br><span class="line">    	<span class="comment">// ...</span></span><br><span class="line"></span><br><span class="line">b)</span><br><span class="line">	<span class="type">int</span> ix;</span><br><span class="line">    <span class="keyword">for</span> (ix != sz; ++ix)  &#123; <span class="comment">/*... */</span> &#125;	<span class="comment">// for 循环少了一条语句且 ix 未被初始化</span></span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">	<span class="keyword">for</span> (<span class="type">int</span> ix = <span class="number">0</span>; ix != sz; ++ix) &#123; <span class="comment">/*... */</span> &#125;</span><br><span class="line"></span><br><span class="line">c)</span><br><span class="line">	<span class="keyword">for</span> (<span class="type">int</span> ix = <span class="number">0</span>; ix != sz; ++ix, ++sz) &#123; <span class="comment">/*...*/</span> &#125;	<span class="comment">// for 循环永远不会停止</span></span><br><span class="line"><span class="comment">// 修改如下</span></span><br><span class="line">	<span class="keyword">for</span> (<span class="type">int</span> ix = <span class="number">0</span>; ix != sz; ++ix) &#123; <span class="comment">/*...*/</span> &#125;</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-17"><a href="#Ex5-17" class="headerlink" title="Ex5.17"></a>Ex5.17</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;vector&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    vector&lt;<span class="type">int</span>&gt; v1,v2;</span><br><span class="line">    <span class="type">int</span> a=<span class="number">0</span>,b=<span class="number">0</span>;</span><br><span class="line">    <span class="keyword">while</span>(cin&gt;&gt;a)</span><br><span class="line">       v1.<span class="built_in">push_back</span>(a);</span><br><span class="line">    cin.<span class="built_in">clear</span>();      <span class="comment">// 清除ctrl z 状态 让 cin &gt;&gt; b 能进行下去 </span></span><br><span class="line">    <span class="keyword">while</span>(cin&gt;&gt;b)</span><br><span class="line">       v2.<span class="built_in">push_back</span>(b);</span><br><span class="line">    <span class="keyword">if</span>(v1.<span class="built_in">size</span>()&lt;v2.<span class="built_in">size</span>())</span><br><span class="line">    &#123;    </span><br><span class="line">        <span class="type">int</span> i=<span class="number">0</span>;</span><br><span class="line">        <span class="keyword">while</span> (i != v1.<span class="built_in">size</span>() &amp;&amp; v1[i] == v2[i])</span><br><span class="line">        &#123;</span><br><span class="line">            ++i;</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">if</span>(i==v1.<span class="built_in">size</span>())</span><br><span class="line">        &#123;</span><br><span class="line">            cout&lt;&lt;<span class="string">&quot; v1 is prefix of v2 &quot;</span>&lt;&lt;endl;</span><br><span class="line">            cout&lt;&lt;<span class="string">&quot; true &quot;</span>&lt;&lt;endl; </span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">else</span>  </span><br><span class="line">            cout&lt;&lt;<span class="string">&quot; false &quot;</span>&lt;&lt;endl; </span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">else</span></span><br><span class="line">    &#123;</span><br><span class="line">        <span class="type">int</span> i=<span class="number">0</span>;</span><br><span class="line">        <span class="keyword">while</span> (i != v2.<span class="built_in">size</span>() &amp;&amp; v1[i] == v2[i])</span><br><span class="line">        &#123;</span><br><span class="line">            ++i;</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        <span class="keyword">if</span>(i==v2.<span class="built_in">size</span>())</span><br><span class="line">        &#123;</span><br><span class="line">            cout&lt;&lt;<span class="string">&quot;v2 is prefix of v1&quot;</span>&lt;&lt;endl; </span><br><span class="line">            cout&lt;&lt;<span class="string">&quot; false &quot;</span>&lt;&lt;endl;</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">else</span></span><br><span class="line">            cout&lt;&lt;<span class="string">&quot; flase &quot;</span>&lt;&lt;endl; </span><br><span class="line">    &#125;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-4-4"><a href="#Exercises-Section-5-4-4" class="headerlink" title="Exercises Section 5.4.4"></a>Exercises Section 5.4.4</h1><h2 id="Ex5-18"><a href="#Ex5-18" class="headerlink" title="Ex5.18"></a>Ex5.18</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line">a) <span class="comment">// 忘记花括号了；修正如下</span></span><br><span class="line">	<span class="keyword">do</span></span><br><span class="line">    &#123;</span><br><span class="line">    	<span class="type">int</span> v1, v2;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;Please enter two numbers to sum:&quot;</span>;</span><br><span class="line">        <span class="keyword">if</span> (cin &gt;&gt; v1 &gt;&gt; v2)</span><br><span class="line">        	cout &lt;&lt; <span class="string">&quot;Sum is: &quot;</span> &lt;&lt; v1 + v2 &lt;&lt; endl;</span><br><span class="line">    &#125; <span class="keyword">while</span> (cin);</span><br><span class="line">   </span><br><span class="line">b) <span class="comment">// while 括号后面的变量必须是事先声明了的； 修改如下</span></span><br><span class="line">	<span class="type">int</span> ival = <span class="built_in">get_response</span>();</span><br><span class="line">	<span class="keyword">do</span></span><br><span class="line">    &#123;</span><br><span class="line">    	<span class="comment">// ...</span></span><br><span class="line">    &#125; <span class="keyword">while</span> (ival);</span><br><span class="line"></span><br><span class="line">c)	<span class="comment">// ival 不能在 while 循环外使用；修改如下</span></span><br><span class="line">	<span class="type">int</span> ival = <span class="built_in">get_response</span>();</span><br><span class="line">	<span class="keyword">do</span> </span><br><span class="line">    &#123;</span><br><span class="line">    &#125; <span class="keyword">while</span> (ival);</span><br></pre></td></tr></table></figure>

<h2 id="Ex5-19"><a href="#Ex5-19" class="headerlink" title="Ex5.19"></a>Ex5.19</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="keyword">do</span> </span><br><span class="line">    &#123;</span><br><span class="line">        string s1, s2;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;Please enter two string :&quot;</span> &lt;&lt; endl;</span><br><span class="line">        <span class="keyword">if</span> (cin &gt;&gt; s1 &gt;&gt; s2)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="keyword">if</span> (s1 &gt; s2)</span><br><span class="line">                cout &lt;&lt; <span class="string">&quot;s2 is less  than s1&quot;</span> &lt;&lt; endl;</span><br><span class="line">            <span class="keyword">else</span> <span class="keyword">if</span> (s1 &lt; s2)</span><br><span class="line">                cout &lt;&lt; <span class="string">&quot;s1 is less than s2&quot;</span> &lt;&lt; endl;</span><br><span class="line">            <span class="keyword">else</span> </span><br><span class="line">                cout &lt;&lt; <span class="string">&quot;two string are equal&quot;</span> &lt;&lt; endl;</span><br><span class="line">        &#125;</span><br><span class="line">    &#125; <span class="keyword">while</span> (cin);</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-5-1"><a href="#Exercises-Section-5-5-1" class="headerlink" title="Exercises Section 5.5.1"></a>Exercises Section 5.5.1</h1><h2 id="Ex5-20"><a href="#Ex5-20" class="headerlink" title="Ex5.20"></a>Ex5.20</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    string str, tmpstr;</span><br><span class="line">    <span class="type">unsigned</span> cnt = <span class="number">0</span>;</span><br><span class="line">    cin &gt;&gt; str;</span><br><span class="line">    tmpstr = str;</span><br><span class="line">    <span class="keyword">while</span> (cin &gt;&gt; str)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (str == tmpstr)</span><br><span class="line">        &#123;</span><br><span class="line">            ++cnt;</span><br><span class="line">            cout &lt;&lt; str &lt;&lt; <span class="string">&quot; occurs twice in succession&quot;</span> &lt;&lt; endl;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        &#125;</span><br><span class="line">        tmpstr = str;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">if</span> (cnt == <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;No word occurs twice in succession&quot;</span> &lt;&lt; endl;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-5-2"><a href="#Exercises-Section-5-5-2" class="headerlink" title="Exercises Section 5.5.2"></a>Exercises Section 5.5.2</h1><h2 id="Ex5-21"><a href="#Ex5-21" class="headerlink" title="Ex5.21"></a>Ex5.21</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;string&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    string str, tmpstr;</span><br><span class="line">    <span class="type">unsigned</span> cnt = <span class="number">0</span>;</span><br><span class="line">    cin &gt;&gt; str;</span><br><span class="line">    tmpstr = str;</span><br><span class="line">    <span class="keyword">while</span> (cin &gt;&gt; str)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (str[<span class="number">0</span>] &gt;= <span class="string">&#x27;A&#x27;</span> &amp;&amp; str[<span class="number">0</span>] &lt;= <span class="string">&#x27;Z&#x27;</span> &amp;&amp; str == tmpstr)</span><br><span class="line">        &#123;</span><br><span class="line">            ++cnt;</span><br><span class="line">            cout &lt;&lt; str &lt;&lt; <span class="string">&quot; occurs twice in succession&quot;</span> &lt;&lt; endl;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        &#125;</span><br><span class="line">        tmpstr = str;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">if</span> (cnt == <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;No word occurs twice in succession&quot;</span> &lt;&lt; endl;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-5-3"><a href="#Exercises-Section-5-5-3" class="headerlink" title="Exercises Section 5.5.3"></a>Exercises Section 5.5.3</h1><h2 id="Ex5-22"><a href="#Ex5-22" class="headerlink" title="Ex5.22"></a>Ex5.22</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> sz = <span class="built_in">get_size</span>();</span><br><span class="line"><span class="keyword">while</span> (sz &lt;= <span class="number">0</span>)</span><br><span class="line">&#123;</span><br><span class="line">	sz = <span class="built_in">get_size</span>();</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h1 id="Exercises-Section-5-6-3"><a href="#Exercises-Section-5-6-3" class="headerlink" title="Exercises Section 5.6.3"></a>Exercises Section 5.6.3</h1><h2 id="Ex5-23"><a href="#Ex5-23" class="headerlink" title="Ex5.23"></a>Ex5.23</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> v1, v2;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Please enter two numbers: &quot;</span>;</span><br><span class="line">    cin &gt;&gt; v1 &gt;&gt; v2;</span><br><span class="line">    <span class="keyword">while</span> (v2 == <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;The second number is zero, please enter another value: &quot;</span>;</span><br><span class="line">        cin &gt;&gt; v2;</span><br><span class="line">    &#125;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;The result is &quot;</span> &lt;&lt; v1 / v2 &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h2 id="Ex5-24"><a href="#Ex5-24" class="headerlink" title="Ex5.24"></a>Ex5.24</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> v1, v2;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Please enter two numbers: &quot;</span>;</span><br><span class="line">    cin &gt;&gt; v1 &gt;&gt; v2;</span><br><span class="line">    <span class="keyword">if</span> (v2 != <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; <span class="string">&quot;The result is &quot;</span> &lt;&lt; v1 / v2 &lt;&lt; endl;</span><br><span class="line">        <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">else</span> </span><br><span class="line">    &#123;</span><br><span class="line">        cerr &lt;&lt; <span class="string">&quot;The second number is zero！&quot;</span> &lt;&lt; endl;</span><br><span class="line">        <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line">&#125; </span><br></pre></td></tr></table></figure>

<h2 id="Ex5-25"><a href="#Ex5-25" class="headerlink" title="Ex5.25"></a>Ex5.25</h2><figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span><span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="keyword">using</span> <span class="keyword">namespace</span> std;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">    <span class="type">int</span> v1, v2;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;Please enter two numbers: &quot;</span>;</span><br><span class="line">    cin &gt;&gt; v1 &gt;&gt; v2;</span><br><span class="line">    <span class="keyword">try</span></span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">if</span> (v2 == <span class="number">0</span>)</span><br><span class="line">            <span class="keyword">throw</span> <span class="built_in">runtime_error</span>(<span class="string">&quot;The second number is zero!&quot;</span>);</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line">    <span class="built_in">catch</span>(runtime_error err)</span><br><span class="line">    &#123;</span><br><span class="line">        cout &lt;&lt; err.<span class="built_in">what</span>() &lt;&lt; <span class="string">&quot; Please enter another value: &quot;</span>;</span><br><span class="line">        cin &gt;&gt; v2;</span><br><span class="line">    &#125;</span><br><span class="line">    cout &lt;&lt; <span class="string">&quot;The result is &quot;</span> &lt;&lt; v1 / v2 &lt;&lt; endl;</span><br><span class="line">    <span class="built_in">system</span>(<span class="string">&quot;pause&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

</article><div class="post-copyright"><div class="post-copyright__author"><span class="post-copyright-meta">文章作者: </span><span class="post-copyright-info"><a href="https://astralcon.gitee.io/blog">astralcon</a></span></div><div class="post-copyright__type"><span class="post-copyright-meta">文章链接: </span><span class="post-copyright-info"><a href="https://astralcon.gitee.io/blog/2022/05/14/Chapter-5-Statements/">https://astralcon.gitee.io/blog/2022/05/14/Chapter-5-Statements/</a></span></div><div class="post-copyright__notice"><span class="post-copyright-meta">版权声明: </span><span class="post-copyright-info">本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target="_blank">CC BY-NC-SA 4.0</a> 许可协议。转载请注明来自 <a href="https://astralcon.gitee.io/blog" target="_blank">A君的秘密基地</a>！</span></div></div><div class="tag_share"><div class="post-meta__tag-list"><a class="post-meta__tags" href="/blog/tags/C-Primer/">C++ Primer</a></div><div class="post_share"><div 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Getting Started</div></div></a></div><div><a href="/blog/2022/05/14/Chapter-10-Generic-Algorithms/" title="Chapter 10: Generic Algorithms"><img class="cover" src="" alt="cover"><div class="content is-center"><div class="date"><i class="far fa-calendar-alt fa-fw"></i> 2022-05-14</div><div class="title">Chapter 10: Generic Algorithms</div></div></a></div><div><a href="/blog/2022/05/14/Chapter-11-Associative-Containers/" title="Chapter 11: Associative Containers"><img class="cover" src="" alt="cover"><div class="content is-center"><div class="date"><i class="far fa-calendar-alt fa-fw"></i> 2022-05-14</div><div class="title">Chapter 11: Associative Containers</div></div></a></div><div><a href="/blog/2022/05/14/Chapter-12-Dynamic-Memory/" title="Chapter 12: Dynamic Memory"><img class="cover" src="" alt="cover"><div class="content is-center"><div class="date"><i class="far fa-calendar-alt fa-fw"></i> 2022-05-14</div><div class="title">Chapter 12: Dynamic Memory</div></div></a></div><div><a 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target="_blank" title="Email"><i class="fas fa-envelope"></i></a></div></div><div class="card-widget card-announcement"><div class="item-headline"><i class="fas fa-bullhorn fa-shake"></i><span>公告</span></div><div class="announcement_content">朝九晚五，健康生活！</div></div><div class="sticky_layout"><div class="card-widget" id="card-toc"><div class="item-headline"><i class="fas fa-stream"></i><span>目录</span><span class="toc-percentage"></span></div><div class="toc-content"><ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-1"><span class="toc-number">1.</span> <span class="toc-text">Exercises Section 5.1</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-1"><span class="toc-number">1.1.</span> <span class="toc-text">Ex5.1</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-2"><span class="toc-number">1.2.</span> <span class="toc-text">Ex5.2</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-2"><span class="toc-number">2.</span> <span class="toc-text">Exercises Section 5.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-4"><span class="toc-number">2.1.</span> <span class="toc-text">Ex5.4</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-3-1"><span class="toc-number">3.</span> <span class="toc-text">Exercises Section 5.3.1</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-7"><span class="toc-number">3.1.</span> <span class="toc-text">Ex5.7</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-8"><span class="toc-number">3.2.</span> <span class="toc-text">Ex5.8</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-3-2"><span class="toc-number">4.</span> <span class="toc-text">Exercises Section 5.3.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-9"><span class="toc-number">4.1.</span> <span class="toc-text">Ex5.9</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-10"><span class="toc-number">4.2.</span> <span class="toc-text">Ex5.10</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-11"><span class="toc-number">4.3.</span> <span class="toc-text">Ex5.11</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-13"><span class="toc-number">4.4.</span> <span class="toc-text">Ex5.13</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-4-1"><span class="toc-number">5.</span> <span class="toc-text">Exercises Section 5.4.1</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-14"><span class="toc-number">5.1.</span> <span class="toc-text">Ex5.14</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-4-2"><span class="toc-number">6.</span> <span class="toc-text">Exercises Section 5.4.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-15"><span class="toc-number">6.1.</span> <span class="toc-text">Ex5.15</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-17"><span class="toc-number">6.2.</span> <span class="toc-text">Ex5.17</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-4-4"><span class="toc-number">7.</span> <span class="toc-text">Exercises Section 5.4.4</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-18"><span class="toc-number">7.1.</span> <span class="toc-text">Ex5.18</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-19"><span class="toc-number">7.2.</span> <span class="toc-text">Ex5.19</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-5-1"><span class="toc-number">8.</span> <span class="toc-text">Exercises Section 5.5.1</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-20"><span class="toc-number">8.1.</span> <span class="toc-text">Ex5.20</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-5-2"><span class="toc-number">9.</span> <span class="toc-text">Exercises Section 5.5.2</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-21"><span class="toc-number">9.1.</span> <span class="toc-text">Ex5.21</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-5-3"><span class="toc-number">10.</span> <span class="toc-text">Exercises Section 5.5.3</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-22"><span class="toc-number">10.1.</span> <span class="toc-text">Ex5.22</span></a></li></ol></li><li class="toc-item toc-level-1"><a class="toc-link" href="#Exercises-Section-5-6-3"><span class="toc-number">11.</span> <span class="toc-text">Exercises Section 5.6.3</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-23"><span class="toc-number">11.1.</span> <span class="toc-text">Ex5.23</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-24"><span class="toc-number">11.2.</span> <span class="toc-text">Ex5.24</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#Ex5-25"><span class="toc-number">11.3.</span> <span class="toc-text">Ex5.25</span></a></li></ol></li></ol></div></div><div class="card-widget card-recent-post"><div class="item-headline"><i class="fas fa-history"></i><span>最新文章</span></div><div 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